This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The Roche Diagnostics/Hitachi 911 method for total-amylase activity is suitable for the measurement of salivary amylase activity. The Thermo Appliskan microplate reader is a suitable substitute for the Dynatech Lab MRX microplate reader with the Salimetrics method for salivary amylase activity. Our first specific aim is to compare the Roche Diagnostics/Hitachi 911 method for total-amylase activity to the Salimetrics method for salivary amylase activity utilizing the Dynatech Lab MRX microplate reader, with both pooled saliva and individual saliva specimens, for accuracy, precision, dynamic range, and agreement between methods. Our second specific aim is to compare the performance of the Thermo Appliskan microplate reader to the performance of the Dynatech Lab MRX microplate reader with the Salimetrics method for salivary amylase activity, utilizing both pooled saliva and individual saliva specimens, for accuracy, precision, dynamic range, and agreement between methods.